Mosquitoes are important
pests because their biting activity often interferes with outdoor activities
and can transmit disease organisms to people and domestic animals. Most
mosquitoes are active during twilight hours and at night; however, around
the home, the mosquitoes that breed in discarded containers are active
during the day. Mosquitoes need water to complete their life cycle. They
can breed in almost any source of water. Pesticides are only a short-term
solution to nuisance mosquito problems. Solving the problem effectively
and safely requires:

Proper identification of the mosquito species.

Obtaining information about the biology and behavior
of these particular species.

Locating and eliminating breeding sites, particularly
artificial sites that may be as close as your own backyard.

Mosquito
Life Cycle

All mosquitoes have one common
requirement--they need water to complete their life cycle. Some mosquitoes
lay individual eggs on the sides of treeholes or discarded containers, or
in depressions in the ground that will hold water. The eggs can lay dormant
for several years. Some eggs will hatch when they are flooded by rainfall.
Several flooding and drying cycles are usually required for all of the eggs
to hatch that are laid by a particular female mosquito. Other mosquitoes
lay eggs directly on the surface of water. The eggs are attached to one
another to form a raft or the individual eggs float on the water. These
eggs hatch in 24-48 hours releasing larvae that are commonly called "wrigglers"
because you can often see the larvae wriggling up and down from the surface
of the water. Generally, the larvae feed on microorganisms and organic material
in the water, but some mosquitoes prey on the larvae of other mosquito species
and are regarded to be beneficial. In about 7-10 days after eggs hatch,
larvae change to the pupal or "tumbler" stage in preparation for adult life.
Female mosquitoes begin searching for an animal to feed on several days after
emerging from water. Male mosquitoes mate with females one to two days after
the females emerge. Males do not bite, but they do feed on plant juices.

Since mosquitoes need water to
complete their life cycle, the source of a mosquito problem can be just
about anywhere that water can collect. Farm ponds and lakes are typically
not major mosquito breeding areas if they contain fish and are free of weeds,
algae or floating debris in which mosquito larvae can hide. Municipal and
farm animal waste lagoons may become breeding sites. Permanent natural bodies
of water, such as swamps, usually contain a wide variety of predatory insects
and fish that keep mosquitoes from reaching severe nuisance levels, although
storms, such as hurricanes, may disrupt this system and allow mosquito populations
to rise rapidly. In residential areas, human activities often create mosquito
breeding sites or increase the production of mosquitoes in natural bodies
of water. For example, road building and maintenance often impede the drainage
of runoff from rainfall, creating a mosquito breeding site. Clogged drainage
ditches along roads can become productive mosquito breeding sites. Logging
and construction activities often leave tire ruts in the soil. These depressions
are ideal breeding sites for "floodwater" mosquito species. Around the home,
natural tree holes and man-made objects such as bird baths, boats, canoes, discarded tires, and plant pots collect rainwater and allow mosquitoes to breed literally
right in our own backyard. Stagnant water in unused or poorly-maintained swimming pools becomes
an ideal breeding site. This can be a particular problem on homes that are vacant (e.g., foreclosures). You can help reduce mosquito populations by eliminating
or properly maintaining these problem spots:

Some mosquito species may fly only short distances, but they may still be able to invade your property from surrounding areas in your neighbood. Other species can fly several miles from their breeding sites. As a result, efforts by individuals
to control mosquitoes on their property often have limited success. A community-wide
effort may be needed to reduce mosquitoes to tolerable levels. This
may require the formation
of a local mosquito control program to organize community-wide "clean
up" efforts and to determine the need to treat breeding sites or to apply
insecticidal sprays to control adults.

Repellents

Some personal protection from
mosquitoes can be achieved through the use of insect repellents. Many
of these products contain DEET (N,N-diethyl-m-toluamide), but the Centers for Disease Control and Prevention has updated its list of suggested repellent products. Select
the desired formulation (e.g., lotion, aerosol spray or cream) containing
the highest percent of active ingredient, as stated on the product label,
and apply it to exposed skin. Repeated use of repellents over a short
period of time is not recommended, especially for children and pregnant women.
For additional information on repellent products, see the Insect
Note ENT/rsc-5 - Insect Repellent Products

Candles containing oil of citronella
are often used outdoors to repel mosquitoes from around decks and picnic
tables. These products work best when there is relatively little air movement
to disperse the chemical too quickly. Avoid splashing
water on lit citronella candles.

Non-chemical Control Measures

Installing and maintaining
tight fitting screens on doors and windows will help keep mosquitoes out
of the home.

Bats and birds,
such as Purple Martins,
may consume mosquitoes as part of their diet. You can install nesting
boxes around your property to attract these natural predators to the area.
However, bear in mind that the feeding activity of insect-eating bats
and birds may not be sufficiently selective to cause noticeable reductions
in mosquito populations. Also, many of our major mosquito problems occur when some predators are inactive (or less active). For example, the Asian tiger mosquito is most active between 10:00am and 3:00pm when bats are normally roosting.

What Doesn't
Work

Electrocutor traps ("bug zappers")
placed out of doors are not effective in reducing or eliminating
mosquito populations. Studies have shown that less than ¼
of 1% of the insects "zapped" in such devices were actually biting insects.
The majority of the insects killed in electrocutor traps are actually
beneficial in some form. Electronic mosquito repellers that emit high
frequency sound to "repel" mosquitoes have not been shown to be effective.

Several
types mosquito traps that use radiant heat and/or chemicals such as carbon
dioxide or octenol to attract mosquitoes are now being marketed in the
U.S. To date, there are no scientifically-based studies that prove that
these traps are able to provide control of local mosquito populations.
Some mosquito species such as Asian tiger mosquito are not attracted
to these particular chemical cues.

Similarly, claims that certain
plants placed around a porch or deck will repel mosquitoes are not supported
by any scientifically-based test results.

Chemical Control
Chemical control of mosquitoes
primarily targets the adult. Outdoor foggers will keep mosquitoes away for
several hours, but once the chemical dissipates, mosquitoes may return to the area.
Spraying thickets or shrubs along the perimeter of your yard helps reduce
the population of mosquitoes that rest in these areas. However, some species of mosquitoes may move readily back into these areas from surrounding untreated places. Consult the
NC Agricultural Chemicals Manual
or your county Cooperative Extension
Center for more information on selecting appropriate pesticides for
use against mosquitoes.

Insecticides are available for controlling larvae, but their application
in either large bodies of water or small artificial breeding sites can be
difficult and expensive, particularly for an individual homeowner. Control
programs targeting mosquito larvae are best left to trained individuals
in county
or local government agencies. Most of these chemicals are not selective
and some may even harm beneficial insects and other non-target organisms.
Furthermore, use of these chemicals will provide only temporary reduction
in mosquito populations. Modifying or eliminating breeding
sites is the only long-term solution to severe mosquito problems.

Homeowners wanting to treat small areas, such as bird baths, garden pools,
etc, might want to try a bacterial insecticides that are available at many
retail stores, garden centers and on-line garden suppliers. There are several products formulated as "donuts" ("dunks") or as granules that contain the bacterium
Bacillus thuringiensis israelensis or "Bti". This
bacterium kills mosquitoes, but does not harm fish, birds or other wildlife.
The "dunk" versions are well-suited for small breeding sites (100 sq. ft. or
less) and will control mosquito larvae for about 30 days. Before using Bti products, you need information on the life cycle and habitat requirements of mosquitoes in your area. Simply treating all areas of standing water
without knowing if they are actually sources of the problem is a
waste of time and money.

Mosquito
Species Identification

There are at least 60 species of mosquitoes found in North Carolina (Harrison, 2008 survey). Since the habitat
requirements of mosquito species are known, proper identification of the
mosquitoes can be used to obtain information on where to search for and
identify likely breeding sites. Collect some mosquito specimens for identification.
Adult mosquitoes attempting to land are easily collected by placing a small
jar (such as a baby food jar) over them. If possible, collect several dozen
specimens. Place the jar in a freezer overnight. Spread the mosquitoes between
sheets of facial or toilet tissue to protect them from being damaged, then
place them back in the jar. Take the specimens to your county Cooperative
Extension Service Center where arrangements can be made to identify
the specimens and provide you with the information you need on how to control
your mosquito problem.

Pest information and control
recommendations presented here were developed for North Carolina and may
not be appropriate for other states or regions. Any recommendations for
the use of chemicals are included solely as a convenience to the reader
and do not imply that insecticides are necessarily the sole or most appropriate
method of control. Any mention of brand names or listing of commercial
products or services in the publication does not imply endorsements by
North Carolina Cooperative Extension nor discrimination against similar
products or services. All recommendations for pesticide use were legal
at the time of publication, but the status of pesticide registrations
and use patterns are subject to change by actions of state and federal
regulatory agencies. Individuals who use chemicals are responsible for
using these products according to the regulations in their state and to
the guidelines on the product label. Before applying any chemical, always
obtain current information about its use and read the product label carefully.
For assistance, contact the Cooperative
Extension Center in your county.

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